docs(ngMock): fixes in flush() documentation

The docs for the `flush()` method contained a few grammatical
errors and were awkwardly worded. Change the explanation of
the method to remove errors and read more naturally.

Closes #4886
docs(loader): change 'MyModule' -> 'myModule'

Closes #5393
docs(guide/injecting-services): fix list formatting in Related* sections

Closes #5447
docs(*): ensure jsdoc type expressions are valid
chore(package.json): update dgeni dependencies